Check out these screen captures. Even with LCA's parallel to the ground the roll center is still basically subterranean. We are thinking about doing what the BRE dudes did. Raising the inner LCA pivot an 1" then lowering the outer tie rod enough to fix the bump steer. First we are going to see what it does on the computer. This what the BRE dudes did. See how the tie rod arm swoops down on the steering knuckle. I just imagine that it narrows the usable good bump area to a pretty small margin. If thats what it takes to win!!!!

Sam has really been going to town on Solid Works. He's got it programed now so we can click between LCA angles. It made doing this so easy. It's really going to pay off in the upcomming weeks sorting out the perfect race crossmember. Which of coarse we are going to make and sell a rack and pinion crossmember too. Ours will have to be slightly better though JK!

"People don't like it when shit doesn't match their rule of thumb." Sam

Don can mod the steering knuckles for you...he did mine and as well raised the LCA pivot up a little more than an inch. My race car is in the trailer hibernating right now, if I can get it into the shop soon I'll snap some pics. Need to start prepping for the spring season....it'll be here before I know it. The heim jointed tie rods are nice for bump steer...you drill the taper out of the knuckle and use a shouldered bolt with shims to raise and lower the pivot point of the outer. It'll be interesting to see how your rack solution fits into this package.

I thought I would throw this up here, just as a general FYI. Not to hijack Jeff's thread, but, to maybe let you get a better understanding of what driving is all about, at least from a performance perspective. I watch with great interest as Jeff heads to making his car handle.

As we all head to get the "BEST" parts on our car, and, have the "perfect" set up and alignment, we never really talk about the actual art of driving on this site.

Back in the 70's, Mark Donahue was one of my hero drivers, actually having a very brief conversation with him one very early morning, at Seattle International Raceway. I was there at the crack of dawn for the Formula 5000 race, which Donahue was to participate in. I was walking the fence one way and he was out for a pensive walk going the other way. I said hi and we passed a few pleasantries, then I wished him luck.

It was not long after this that I got serious about my racing and started to get books on the subject, one being TUNE TO WIN by Carroll Smith and HOW TO MAKE YOUR CAR HANDLE by Fred Puhn. Both became my bibles for many years.
In Tune To Win, Carroll talks about Mark Donahue's theory of the "TRACTION CIRCLE" ( page 24 ), or as I now call it "The Circle of Life". EXCEED your traction limit, in any one direction, and it can get ugly fast. And, to be fast at driving, you need to both maintain grip and maximize the grip you have...WITHIN the traction circle.

Understanding this leads to understanding WEIGHT transfer in our 510's, which while I am far from an expert, can give you a fantastic ride to say the least. Given that we end up with a fairly balanced handling package after throwing all our money at these fancy parts, maximizing the weight transfer is what driving is all about IMHO. Knowing WHEN to get off the brakes in a corner can maximize the front bite big time. All of this requires you to both KNOW the final grip limit of your tire and your suspension capability, which then becomes the art of driving. Put all this together and it does not matter WHAT you are driving, you will be able to maximize the cornering capability of that particular package. I have left many a sporty car in the dust in corners with my Honda Odyssey, as the guy behind me expects to see brake lights and is driving MY line. Being able to "TOSS" a vehicle into a corner and hit that final grip point and no more, weeds out 99.9% of most drivers, as they have no clue as to their final traction point.

The term "TOSS" is maybe a misnomer, as it is really a very precise point in corner entry, where you use the steering wheel to start the weight transfer onto a front tire, in a very rapid but controlled movement, which if you stay within the traction circle for cornering, lets the whole vehicle take a "SET" and will follow your intended line THROUGH that corner, at maximum grip, with no more movement on the steering wheel. This is where SLOW HANDS comes into play, no more sawing at the wheel, as this totally disrupts the weight transfer. It take very little lifting of the throttle to mess things up. When I instructed Solo driving school, we talked about "squeezing" the steering wheel...LITERALLY. That subtle flexing of your wrist and hand muscles will be enough to correct any deviation of steering input. Believe me, try it in your regular street ride on on-ramps, pick a line and constant radius, then, just squeeze the wheel, and watch the change. I still practice this daily on my commute.

I hope I have explained this at least a little bit, but, do read the attached links to the traction circle. Understand this and you will have a big jump on the next guy who does not.

Thanks Keith! I'll check out those books! A intern at my work built a computer simulator, like with a racing seat and everything. Not in my wildest dreams did I think it would help in real life! He held the top time at the go-cart track next to my work all that summer!!! I want to build one now

"People don't like it when shit doesn't match their rule of thumb." Sam

great links Bert I will give them a read.....I have not tried "squeezing" as you describe but to keep with you on our runs in my jacked up snow tire supporting dime. I find my hands are not slow and that I must dip the wheel (give it a little shake or rock) when in the big bends like the carousels between Manning and Princeton. why does the car tell me to do that (or maybe) why do I think Its needed?

In reality, we have bumps in corners (bump steer), tread design starting to exceed design limitations ( which in your case is right off the bat..HA), some guy on your ass who is pushing you hard into a corner, so you get on the throttle more, which then changes the weight transfer and hence the intended line, or, the guy ahead of you chickens out on HIS line, and when you hit the brakes all bets are off for just "squeezing " the wheel.

You think it is needed because THAT is what keeps you on the road.....

The more deflection in tires and suspension bits is what really happens, again in reality, that you end up moving your hands a lot. I was only trying to make the point of being as smooth as possible, which during our Canyon runs is actually quite hard, as at some points, even I exceed my traction point in the circle of life...JUST. Our last drive with Norm and Richard on my bumper at a couple of points had my rear end slip just a hair, which, if we keep EVERYTHING slowed down as much as possible, does not lead us over correct, which then could lead to a tank slapper or off road excursion.

It's understanding what is happening that is important, not how you keep the car on the road. Reading road surface also is a key component in anticipating what is going to happen too. Think of some of those corners through Manning, smooth going in, then, broken pavement at the apex, which you need to allow for how that will throw the car.

Those are some great pointers Keith. I found with the tires on my car it really pays to be smooth. With zero understeer from them it is really easy to overcorrect if you move too fast. Also having a pretty large slip angle before they let go really teaches you to trust your car. You don't need to be flailing around and working the pedal.....unless you want to be sideways that is.

If no one from the future comes back to stop you from doing it then how bad of a decision can it really be?

Built new sway bar brackets which allowed me to sand the rubber part thinner which raised the sway bar. At 16 degress of LCA angle the tire hits the frame. Raising the sway bar and adding longer end links should be enough. Just in case I'm going to build taller bump steer spacers (I hate calling them that!) Here are some pictures.

First modify the model Sam made for his car. Which I modified twice but only got pics of the second version but built the fisrt version...

Drawing version 2 even though I built version one. Which is a damn good thing it barely fit!

Programmed in my mill

Milling

installed with LCA at max compression. I don't know what happened to the bushing. I only sanded the one side. Maybe the heat messed with it.

"People don't like it when shit doesn't match their rule of thumb." Sam

First place in RWD!!!!!!!!!! Second fastest time of the day!!! An new AWD turbo porsche got me by just a little he was able to shift to 4th before the finish line! The last straight away allows the high HP guys to make up some time. HHHMMM maybe I need a turbo! I seriously couldn't believe the difference having suspension travel and nice tires made! The best part was all the dudes who actually came up to ask how I was so fast and what they were missing. They couldn't believe I was SECONDS ahead of there AWD Skyline or STI swapped subi, I even beat a twin turbo viper with slicks, and a track only V8 rx7 with 12" slicks. Really I couldn't believe it either! There were over 40 cars and almost every one was nice. I think I was the only car with rust on the outside haha. I'm super happy I didn't mess up my car. One guy hit the wall and another bent some suspension going off track. It's an intense place to race.

O and yes the front tires rub. Just keeps them nice and heated for next laps.

"People don't like it when shit doesn't match their rule of thumb." Sam